refactor(engine): align namespaces with directory layout under OpenNest.Engine

All 132 OpenNest.Engine source files now declare namespaces matching
their nested directories: Jobs/, Jobs/Placement/, Jobs/Adapters/,
Fill/, RectanglePacking/, CirclePacking/, and engine-root types moved
from 'OpenNest' to 'OpenNest.Engine'. RootNamespace updated accordingly.
Consumers (Api, Console, Mcp, Benchmark, Training, desktop app, tests)
gained the explicit usings the move requires; CLAUDE.md updated.

OpenNest.Tests/Api/NestResponsePersistenceTests.cs

@@ -6,6 +6,7 @@ using System.Threading.Tasks;
 using OpenNest.Api;
 using OpenNest.Geometry;
 using OpenNest.IO;
+using OpenNest.Engine.Jobs;
 
 namespace OpenNest.Tests.Api;
 

OpenNest.Tests/Api/NestRunnerTests.cs

@@ -6,6 +6,7 @@ using OpenNest.Api;
 using OpenNest.Converters;
 using OpenNest.Geometry;
 using OpenNest.IO;
+using OpenNest.Engine.Jobs;
 
 namespace OpenNest.Tests.Api;
 

OpenNest.Tests/Benchmark/BenchmarkRunnerTests.cs

@@ -1,4 +1,5 @@
 using OpenNest.Benchmark;
+using OpenNest.Engine.Jobs;
 
 namespace OpenNest.Tests.Benchmark;
 

OpenNest.Tests/Benchmark/JobLoaderManifestTests.cs

@@ -1,5 +1,6 @@
 using OpenNest.Benchmark;
 using OpenNest.Geometry;
+using OpenNest.Engine.Jobs;
 
 namespace OpenNest.Tests.Benchmark;
 

OpenNest.Tests/Engine/EngineOverlapTests.cs

@@ -2,6 +2,7 @@ using OpenNest.Converters;
 using OpenNest.Geometry;
 using OpenNest.IO;
 using Xunit.Abstractions;
+using OpenNest.Engine;
 
 namespace OpenNest.Tests.Engine;
 

OpenNest.Tests/Engine/EngineRefactorSmokeTests.cs

@@ -1,4 +1,5 @@
 using OpenNest.Geometry;
+using OpenNest.Engine;
 
 namespace OpenNest.Tests.Engine;
 

OpenNest.Tests/Engine/MultiPlateNesterTests.cs

@@ -7,6 +7,7 @@ using OpenNest.Geometry;
 using OpenNest.IO;
 using Xunit;
 using Xunit.Abstractions;
+using OpenNest.Engine;
 
 namespace OpenNest.Tests.Engine;
 

OpenNest.Tests/Engine/NestPhaseExtensionsTests.cs

@@ -1,3 +1,4 @@
+using OpenNest.Engine;
 namespace OpenNest.Tests.Engine;
 
 public class NestPhaseExtensionsTests

OpenNest.Tests/Engine/NestProgressTests.cs

@@ -1,4 +1,5 @@
 using OpenNest.Geometry;
+using OpenNest.Engine;
 
 namespace OpenNest.Tests.Engine;
 

OpenNest.Tests/Engine/PlateOptimizerTests.cs

@@ -1,4 +1,5 @@
 using OpenNest.Geometry;
+using OpenNest.Engine;
 
 namespace OpenNest.Tests.Engine;
 

OpenNest.Tests/Fill/AccumulatingProgressTests.cs

@@ -1,4 +1,5 @@
 using OpenNest.Engine.Fill;
+using OpenNest.Engine;
 
 namespace OpenNest.Tests.Fill;
 

OpenNest.Tests/Fill/BestCombinationTests.cs

@@ -1,3 +1,4 @@
+using OpenNest.Engine.Fill;
 namespace OpenNest.Tests.Fill;
 
 public class BestCombinationTests

OpenNest.Tests/Fill/FillLinearCircleTests.cs

@@ -8,6 +8,7 @@ using OpenNest.Geometry;
 using OpenNest.Math;
 using Xunit;
 using Xunit.Abstractions;
+using OpenNest.Engine;
 
 namespace OpenNest.Tests.Fill
 {

OpenNest.Tests/Fill/IterativeShrinkFillerTests.cs

@@ -1,5 +1,6 @@
 using OpenNest.Engine.Fill;
 using OpenNest.Geometry;
+using OpenNest.Engine;
 
 namespace OpenNest.Tests.Fill;
 

OpenNest.Tests/Fill/PairFillerTests.cs

@@ -1,5 +1,6 @@
 using OpenNest.Engine.Fill;
 using OpenNest.Geometry;
+using OpenNest.Engine;
 
 namespace OpenNest.Tests.Fill;
 

OpenNest.Tests/Fill/PairOverlapDiagnosticTests.cs

@@ -3,6 +3,7 @@ using OpenNest.Engine.Fill;
 using OpenNest.Geometry;
 using OpenNest.Math;
 using Xunit.Abstractions;
+using OpenNest.Engine;
 
 namespace OpenNest.Tests.Fill;
 

OpenNest.Tests/Fill/RemnantFillerTests2.cs

@@ -1,5 +1,6 @@
 using OpenNest.Engine.Fill;
 using OpenNest.Geometry;
+using OpenNest.Engine;
 
 namespace OpenNest.Tests.Fill;
 

OpenNest.Tests/Fill/ShrinkFillerTests.cs

@@ -1,5 +1,6 @@
 using OpenNest.Engine.Fill;
 using OpenNest.Geometry;
+using OpenNest.Engine;
 
 namespace OpenNest.Tests.Fill;
 

OpenNest.Tests/Strategies/FillPipelineTests.cs

@@ -1,5 +1,6 @@
 using OpenNest.Engine.Strategies;
 using OpenNest.Geometry;
+using OpenNest.Engine;
 
 namespace OpenNest.Tests.Strategies;
 

OpenNest.Tests/Strategies/StripeFillerTests.cs

@@ -3,6 +3,7 @@ using OpenNest.Engine.BestFit;
 using OpenNest.Engine.Fill;
 using OpenNest.Engine.Strategies;
 using OpenNest.Geometry;
+using OpenNest.Engine;
 
 namespace OpenNest.Tests.Strategies;